I've been in street fights, but there are in fact "rules" that should be respected when it's 1 v 1.
-Never start shit unless you're ready to finish it, or ready to accept the consequences (such as getting you're ass kicked)
-No weapons
-No sucker punches/blind sides
-No more hitting when he's down
-If you knock him out, at least make sure he's still breathing, that he won't choke on his tongue and that someone (a friend or other) can take care of getting him help if needed
When the numbers are un-even, then none of these rules apply.
The guys who can't respect or fight by these minimum rules are those who KNOW they don't stand a chance when fighting fair...or are just plain criminals who would kill the guy if they knew they wouldn't get caught.
A friend of mine was killed almost 2 years ago because of a coward who stabbed him after realizing he wouldn't win the fight fairly. A fight this coward started because he couldn't accept the fact that my friend was now dating his EX...Now that guy has been convicted for 25 to life, but I'm still short a friend.